FAULTBASE
NEWSASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Honda/CR-V/Sixth Generation (2023-present)/how to diagnose a P0420 code on my Honda CR-V Fifth Generation (2017-2022)

how to diagnose a P0420 code on my Honda CR-V Fifth Generation (2017-2022)

Honda CR-V Sixth Generation (2023-present)

Severity: highDifficulty: mediumError Code: P04202-4 hours
3 min read
489 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0420 exhaust system efficiency issue in Honda CR-V (2017-2022). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0420
Component
Exhaust System
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect battery before working on electrical systems.
  • ⚠Allow the exhaust system to cool before inspection and repair.

Symptoms

  • •Check engine light illuminated
  • •Decreased engine performance
  • •Poor fuel economy
  • •Unusual exhaust smell (sulfur or rotten egg)
  • •Failed emissions test
  • •Rough idle

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm P0420 and check for additional codes.
  2. 2Inspect the exhaust system visually for leaks, cracks, or damage.
  3. 3Check the condition of the oxygen sensors (upstream and downstream) for proper operation and connections.
  4. 4Test the voltage output of the upstream and downstream oxygen sensors using a multimeter.
  5. 5Verify the catalytic converter's temperature using an infrared thermometer to compare inlet and outlet temperatures.
  6. 6Inspect for any exhaust restrictions or blockages that may impact flow.

Solution

Solution

1. Preparation

  • Gather tools and parts.
  • Disconnect the battery to prevent electrical shorts.
  • Raise the vehicle safely on jack stands.

Tools Required:

  • OBD-II scanner
  • Multimeter
  • Infrared thermometer
  • Socket set
  • Torque wrench

2. Inspect and Replace Oxygen Sensors

  • Sub-steps:
    1. Locate the upstream and downstream oxygen sensors on the exhaust system.
    2. Disconnect the electrical connectors from both sensors.
    3. Use the socket set to remove the sensors from the exhaust pipes.
    4. Install new oxygen sensors and torque to manufacturer specifications (typically around 30 ft-lbs).
    5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if needed)

  • Sub-steps:
    1. Remove any heat shields or brackets securing the catalytic converter.
    2. Disconnect the exhaust pipes connected to the catalytic converter using the socket set.
    3. Remove the old catalytic converter.
    4. Install the new catalytic converter, ensuring all gaskets are in good condition.
    5. Reconnect the exhaust pipes and heat shields, torquing bolts to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

  • Sub-steps:
    1. Reconnect the negative battery terminal.
    2. Use the OBD-II scanner to clear the P0420 trouble code from the vehicle's computer.

Verification

After completing the repair, verify that the issue has been resolved:

  • Test the affected component to ensure it functions correctly
  • Check for any error codes or warning lights
  • Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • OBD-II scanner
  • Multimeter
  • Infrared thermometer
  • Socket set
  • Torque wrench

Parts Required

  • Upstream oxygen sensor
  • Downstream oxygen sensor
  • Catalytic converter (if replacement is necessary)

Additional Information

Error CodeP0420
Component

Exhaust System

Repair Time

2-4 hours

Difficulty

medium

Severity

high

Tools

5 items

Parts

3 items

Related Faults

Discover similar issues

  1. how to reset the maintenance light on Honda CR-V Sixth Generation (2023-present)

    Learn how to reset the maintenance light on Honda CR-V Sixth Generation (2023-present) with this simple step-by-step guide. No tools required.

    Component:Electrical
    Symptoms
    • •Maintenance light illuminated on the dashboard
    • •No other engine warning lights present
    • +{count} more
  2. my Honda CR-V has a strong oil smell what does it mean

    Learn how to diagnose and fix a strong oil smell in your Honda CR-V. Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Engine
    Symptoms
    • •Oil spots on the ground under the vehicle
    • •Engine oil level dropping rapidly
    • +{count} more
  3. how to fix the door locks not working on my Honda CR-V Sixth Generation (2023-present)

    Learn how to diagnose and fix door locks not working on Honda CR-V Sixth Generation. Step-by-step guide with symptoms, diagnostic steps, and solutions...

    Component:Electrical
    Symptoms
    • •Door locks do not respond when using the key fob
    • •Manual lock switches inside the vehicle are unresponsive
    • +{count} more
  4. how to fix P0011 code in Honda CR-V Sixth Generation (2023-present)

    P0011

    Learn how to diagnose and fix P0011 code in Honda CR-V (2023-present). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

    Component:Engine
    Symptoms
    • •Check engine light illuminated
    • •Rough idle or poor engine performance
    • +{count} more
  5. how to reset the check engine light on Honda CR-V Sixth Generation (2023-present)

    Learn how to reset the check engine light on Honda CR-V Sixth Generation (2023-present) with this step-by-step guide. Quick and easy instructions incl...

    Component:Electrical
    Symptoms
    • •Check engine light illuminated
    • •Vehicle may run normally or could exhibit symptoms related to the underlying issue
    • +{count} more
  6. how to check the catalytic converter on my Honda CR-V Sixth Generation (2023-present)

    Learn how to check the catalytic converter on your 2023 Honda CR-V. Step-by-step diagnostic procedures and solutions for performance issues.

    Component:Exhaust System
    Symptoms
    • •Check engine light illuminated
    • •Decreased fuel efficiency
    • +{count} more

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation